Question

Which of the following statements are correct about salts of oxoacids of group 2 elements? \[ \begin{aligned} \text{I. }& \text{Their carbonates are generally insoluble in water.}\\ \text{II. }& \text{Solubility of their sulphates in water decreases from } \mathrm{CaSO_4} \text{ to } \mathrm{BaSO_4}.\\ \text{III. }& \text{Their nitrates undergo decomposition on heating.} \end{aligned} \] The correct answer is

• A. I, II only
• B. II, III only
• C. I, III only
• D. I, II, III

Hint:

For group 2 compounds: \[ \boxed{ \begin{aligned} &\text{Carbonates are insoluble}, &\text{Sulphate solubility decreases down the group}, &\text{Nitrates decompose on heating.} \end{aligned} } \]

Answer 1

The Correct Option is D

Step 1: Check Statement I. The carbonates of group 2 elements are generally insoluble in water. Hence, \[ \boxed{\text{Statement I is correct}.} \]

Step 2: Check Statement II. The solubility of sulphates decreases down the group: \[ \boxed{\mathrm{CaSO_4}>\mathrm{SrSO_4}>\mathrm{BaSO_4}.} \] Hence, Statement II is correct.

Step 3: Check Statement III. On heating, \[ \mathrm{M(NO_3)_2} \rightarrow \mathrm{MO}+2\mathrm{NO_2}+\frac12\mathrm{O_2}. \] Thus, group 2 nitrates undergo thermal decomposition. Hence, Statement III is also correct. Therefore, \[ \boxed{\text{Statements I, II and III are correct}.} \] Hence, the correct option is \(\boxed{(D)}\).